Hydroxyl-terminated hydroxymethylabietanyl adipate

ABSTRACT

Ethylene glycol adipic acid polyester was modified by incorporating the naval stores derived 12hydroxymethyitetrahydroabietanol in the polyester chain. The modified polyester was blended with a poly (ethylene adipate) glycol (mol. wt. 2000) and 1,4-butanediol, Bu(OH)2, giving glycol mixtures which were reacted with toluene diisocyanate TD1. Clear strong polyurethane films (26.6% TDI) from glycol mixtures (average hydroxyl equivalents, OHE, of 252) containing 5, 10, 15, and 20 percent resinyl moiety were prepared and their polymer properties examined. Incorporation of the moiety gave strength, toughness, and stiffness to films which otherwise would have been soft and tacky. Glycol mixtures having higher hydroxyl equivalent values required less isocyanate and addition of the resinyl glycol gave strong elastic films from a composition containing 16.6% TDI. Experimental data suggests that use of the bulky 12hydroxymethyltetrahydroabietanol may be an important contribution to polyurethane technology.

United States Patent Lewis et al.

[ June 27, 1972 [54] HYDROXYL-TERMINATED HYDROXYMETHYLABIETANYL ADIPATE [72] Inventors: John B. Lewis; Glen W. Hedrick, both of Lake City, Fla.

[73] Assignee: The United States 01 America as represented by the Secretary 01 Agriculllllt' [22} Filed: May 12,1970

[21] ApplrNo; 36,673

Primary Examiner-Lorraine A. Weinberger Assistant Examiner-E. Jane Skelly AttorneyR. Hoffman and W. Bier 57 ABSTRACT Ethylene glycol adipic acid polyester was modified by incorporating the naval stores derived l2-hydroxymethyitetrahydroabietanol in the polyester chain. The modified polyester was blended with a poly (ethylene inlipute) glycol (mol. wt. 2000) and 1,4-butanediol, Bu(()ll),, iving glycol mixtures which were reacted with toluene diisocyanatc TDl. Clear strong polyurethane films (26.6% TDl) from glycol mixtures (average hydroxyl equivalents, OHE, of 252) containing 5, 10, 15, and 20 percentresinyl moiety were prepared and their polymer properties examined. Incorporation of the moiety gave strength, toughness, and stiffness to films which otherwise would have been soft and tacky. Glycol mixtures having higher hydroxyl equivalent values required less isocyanate and addition of the resinyl glycol gave strong elastic films from a composition containing 16.6% TDI.

Experimental data suggests that use of the bulky 12-hydroxymethyltetrahydroabietanol may be an important contribution to polyurethane technology.

1 Claim, No Drawings HYDROXYL-TERMINATED HYDROXYMETHYLABIETANYL ADIPATE A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the US. Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

CHzOH CH20-- I CHzOH R I (II) R=CO;--

(III) R=OH2O-- O i CH OJIi (CH2)4C O CzH OH Pine oleoresin (pine gum), the exudate from the living pine tree, contains from 18 to 25 percent levopimario acid, and since its reaction in situ in gum with formaldehyde is essentially quantitative, gum might be considered an economical source for the abietanol derivative. The glycol is easy to obtain pure. Initial experiments to use it in polyurethanes demonstrated problems resulting from insolubility characteristics and melting point of 183 C. This invention shows the results of incorporating the hydroxymethylabietanol derivative in hydroxyl-terminated polyglycol adipates to overcome the adverse physical properties and then use of the modified glycol adipates in polyurethane elastomers.

Polyester urethane thermoplastic polymers are becoming more popular industrially because of the unique properties obtainable by changes in formulations which result-in markets formerly filled by use of one or more old line plastics.

A study was undertaken to determine the effect the bulky resinyl moiety had on the properties of polyester-derived urethane polymers. In a related paper Lewis and Hedrick [1&EC, Prod. Res. & Dev., in press (l969)] describe polyurethanes made from polypropylene glycols modified by incorporating the resinyl moieties ll and Ill in the polyether chain.

To evaluate the resinyl glycol (l), the glycol was reacted with 2 mole equivalents of adipic acid and the resulting adipate was heated with excess ethylene glycol until the acid value indicated the acid had all reacted. This glycol was then blended with poly(ethylene adipate) glycol (OHE, approximately l000) and l,4-butanediol and the glycol blend reacted with diisocyanate. In the first experiments TDl was used and since the results were meaningful and perhaps unusual, this isocyanate was used throughout to prepared polymers in a l2-hydroxymethyltetrahydroabietic acid could not be made without considerable ester interchange. The same was true of the ethylene glycol ester of this acid.

Early workers concluded the optimum molecular weight of the poly (ethylene adipate) glycol was 2,000, and also report data showing that 1,4-butanediol was probably superior to other commercially available aliphatic diols when used as an extender.

Early workers reacted the poly (ethylene adipate) glycol with excess 4,4-diphenylmethyl diisocyanate to obtain an isocyanate-terminated polyurethane which was reacted with the extender to produce high molecular weight (30 to 50,000) polyurethanes. Early experiments with resinyl glycols, employing a two-step process using butanediol as an extender gave polymers having tensile properties almost identical to those obtained using a one-step process. It was concluded that the combined effectsof TDI and the resinyl moiety masked the differences resulting from a two step preparation.

In the present invention, polyurethanes from TDI and a mixture of poly (ethylene adipate) glycol (mol. wt., 2,000) and butanediol were soft and weak with an average hydroxyl equivalent of the glycol mixture of about 250. An incorporation of 5 percent of the resinyl material (lll) in the formulation had a marked increase in the tensile properties. Additional increases of l0, l5, and 20 percent resulted in films having increased strength and stiffness (items 1 to 4, Table 1) and at 25 percent the hot polymer mixture was too viscous to handle and was hard and brittle cold. The average Ol-lE of the glycol mixture in this series was held at 252 and the maximum variance in resinyl composition with this OHE value was from 5 to 20 percent because of the elastic properties of the film. The resinyl compound (Ill) requirement was less for polyurethanes made from glycol mixtures with lower average molecular weights. The opposite effect was observed when the average molecular weight of the mixture was increased (Item 5, Table 1). Since the NCO:Ol-l ratio was in each case 1.05:1, an increase in molecular weight called for less isocyanate.

The literature references above state that aromatic rings phenyl or naphthalene and branching of methyl groups have the greatest effect on modulus.

Pigott et al. [1. Chem. Eng. Data 5, 391 (1960)] state that because of increased bulkiness and rigidity of naphthalene diisocyanate when compared with p-phenylene diisocyanate in urethanes, substantial increases in hardness and 300 percent modulus were noted. When TDl was compared with pphenylene diisocyanate the effect of the reduced symmetry combined with the methyl substituents was demonstrated by a general decrease in tensile, modulus, tear, and hardness. When comparing polyester glycols, the tensile and modulus of the elastomers made from a polyester containing methyl side .chains were significantly lower than for the elastomers prepared from linear polyesters.

Cone. Taber of III Poly abra- Durorn- Polyin (ethyl- Ave. sion wt. eter ester film, ene OHE Tensile Modulus, p.s.i., Elonga- Brittle Stiifloss Shore (IV) per- BIRCH): adipate) glycol strength tion, point, ness, percent A Item equiv. cent equiv. equiv. mix p.s.i. 100% 200% 300% percent" 0. TP 0. 10- hardness OHE, 343. d Pigott et a1. (1960), Table 1; TDI (1960)] Table 2, Poly(tetramethylene adipate) glycol, 0.2 equ1v.; 1,4-b1s (2 At this time the reasons for the effect of incorporating the glycol (1) in the polyurethane chain is not clear. The resinyl group is far more bulky and has a greater number of alkyl sub stituents than materials heretofore investigated. The bulkiness should result in an increase in modulus which is demonstrated by date in Table 1. Based on published data above, the lack of symmetry and the presence of the alkyl substituents combined with the effects of TDI in the polymers should have resulted in films with reduced strength. This was not the case.

The increase in strength resulting from addition of 1 may result from entanglement; however, evidence against this is the complete recovery of specimens after stretching almost to the breaking point. The recovery rate, however, decreases with increase in incorporation of 1.

Item 5 in Table 1 has the following composition percent: glycol (1V), 55.6; poly (ethylene adipate) glycol, 27.77; and TD], 16.63. This was added to demonstrate briefly the possibilities which might be achieved by variations in formulations and to show the effect of an increased average OHE, in particular, as this increase relates to the amount of TDI required. items 6 and 7 are taken from the literature and are inserted for comparison purposes.

EXAMPLE 1 Hydroxyl-terminated Hydroxymethylabietanyl Adipate (IV) 12-Hydroxymethyltetrahydroabietanol (1) (322.5 g; 1.0 mole) and adipic acid (292 g; 2.0 moles) were heated to 190-200 C while sparging with a slow stream of nitrogen until water of the reaction had all distilled. The product was a colorless, low-melting solid, 576 g; calcd: 578 g.

Anal. calcd for c,,n,,o,= N.E., 288.2. Found: N.E.,294.

Ethylene glycol (186 g; 3 moles) was added and heating (195 C) resumed while slowly sparging with nitrogen. After 2% hours [acid number (AN) 9] ethylene glycol (31 g; 0.5 mole) was added and the batch temperature was raised to 230 C and held about an hour (A.N., 2.8). The temperature was lowered to 100 C and vacuum applied (0.3 mm) for 2 hours to remove excess ethylene glycol, (A.N., 2.2; 658 g).

Anal. calcd for C fl O z OHE, 332.24. Found: OHE, 343. In another experiment, heating under vacuum to remove excess ethylene glycol was continued until a constant weight was obtained.

Calcd: OHE, 332.24; S.E., 166.12. Found: OHE, 358.7; 8.15., 167.6.

b OHE, 358; TDI equiv. for (1) through (4) inc., 0.50; for (5), 0.313; NCOZOH ratio equiv., 1.05:1.

ratio, 1.07:1, Shore B hardness.

0 Taken from bench marks. Schollenberger [Polyurethane Technology, 10, 197

hydroxymethoxy) benzene, 0.3 e ,uiv.; TDI, .50 epuiv.

EXAMPLE 2 leaving 87.28 g in the flask (Item 1, Table 1). G1 col IV was added, heated to 100 C for 15 min., degassed at .2 mm, and

then butanediol added, mixed, and degassed at 100 C at 35 mm. After cooling to 60 C, the TDl was added, mixed at atmospheric pressure, then heated to C at 0.2 mm. pressure until mixing was complete. Some cooling by a water bath was required. The clear liquid polymer mixture was poured hot into molds which consisted of a 6 X 6 inch (inside) aluminum metal frame clamped to a one-fourth inch thick aluminum sheet covered with thin aluminum foil. The metal frames and plate were enclosed in a galvanized, steel, square box covered with plywood which supported a thermometer. The plates were maintained at -1 10 C by a hot plate. The reaction mixture was poured onto the foil in an amount (about 42 g) so that approximately 1/16-inch thick films resulted. Eighteen hours at 100-110 C was required for curing.

The films were cut to remove them from the frames, immersed in dilute mineral acid to dissolve the foil, and washed, then exposed to the atmosphere about one week on the laboratory bench.

Tensile properties of the clear, almost colorless films were run at the Naval Stores Laboratory and other tests were made by commercial laboratories.

All the films using formulations in Table 1 were prepared as above. Results are tabulated in Table 1.

We claim:

1. A compound represented by the formula O O 5 ll OHIO (CH2)A O CzHt 

